The application relates to polyamides of a certain structure and to polyalkenes in which small amounts of these polyamides have been incorporated so as to improve the dyeability of this polyalkene for acid dyestuffs.
It is generally recognized that polyalkenes have a poor dyeability because of the lack of polar groups which can function as points of attachment for dye molecules. Consequently, up to now much attention has been paid to the development of polyalkenes in which the desired polar groups are present and which as a result display good dyeability. Good dyeability is a collective name for good color intensity, a good homogeneity and a good color fastness of the dyed modified polyalkene.
In the literature various polyalkenes modified with basic polyamides have been described. British patent specification No. 1163266, for example, describes polyalkylene that has been modified with a basic compound, for example a polyamide, in which the basic nitrogen groups have been at least partly converted into a salt with the aid of a strong acid. The polyamide used in this manner is built up of aliphatic polyamines, preferably of the formulae: ##STR1## in which R.sub.1, R.sub.2 and R.sub.4 are alkylene groups, preferably C.sub.1 -C.sub.6, and R.sub.3 and R.sub.5 are a hydrogen atom or a C.sub.1 -C.sub.16 alkyl group. Aliphatic, aromatic, cycloalkyl- and alkylaryldiamines can also be used. Carboxylic acids which can be reacted with the polyamines to obtain the polyamide modifiers include aliphatic acids such as succinic acid, glutaric acid, adipic acid, 2,2,4-trimethyl adipic acid, suberic acid, azelaic acid, sebacic acid and dodecanedioic acid, alkyl-substituted aliphatic dicarboxylic acids, dimeric unsaturated fatty acids, aromatic, cycloalkyl and alkylaryl dicarboxylic acids. For a satisfactory dyeing result, neutralization of the basic polyamides with a strong acid is considered necessary.
In U.S. Pat. No. 3,433,853 polyalkenes modified with basic polyamide are described wherein the polyamide is derived from a polyamine containing not more than two primary amino groups and one or more tertiary amino groups and a dicarboxylic acid, including aliphatic, aromatic and hetercyclic acids. One class of useful polyamines have the formula ##STR2## Diamines, particularly aliphatic diamines, can replace part of the polyamine. The Examples describe polyamides which are based on hexamethylenediamine, N,N'-bis(3-aminopropyl)methyl amine and either azelaic or sebacic acid (Example I and Example II(1), respectively).
The known modified polyalkenes, such as those described in the abovementioned references are, however, not entirely satisfactory as far as their dyeability is concerned.